Currently there are numerous consumer electronics communications devices such as portable multimedia players, add-ons for portable multimedia players, cellular telephones, personal digital assistants (PDAs), etc. that support a primary communications connection in addition to one or more secondary communications connections. Considering communication devices such as cellular phones, for example, an increasing number of cellular phones today support both the basic primary cellular communications connection as well as support one or more secondary connections such as Bluetooth and Wireless Local Area Network (WLAN) which permit direct connection between cellular phones. In addition to cellular, WiMAX enabled mobile devices also incorporate one or more secondary communications connections. Other short distance wireless technologies such as ultra wideband (UWB) and others are to be incorporated into mobile devices in the next several years.
Bluetooth is an industrial specification for wireless personal area networks (PAN). Bluetooth provides a way to connect and exchange information between devices such as mobile phones, printers, PCs, laptops, and other digital equipment, over a secure, globally unlicensed short-range radio frequency (RF).
Bluetooth is a radio standard and communications protocol primarily designed for low power consumption, with a short range based on low-cost transceiver integrated circuits (ICs) in each device. Bluetooth networks enable these devices to communicate with each other when they are in range.
Bluetooth capability is increasingly built-in to many new products such as phones, printers, modems and headsets. Bluetooth is appropriate for situations when two or more devices are in proximity to each other and do not require high bandwidth. Bluetooth is most commonly used with phones and hand-held computing devices, either using a Bluetooth headset or transferring files from phones/PDAs to computers.
Bluetooth also simplified the discovery and setup of services, in contrast to WLAN which is more analogous to a traditional Ethernet network and requires configuration to set up shared resources, transmit files, set up audio links (e.g., headsets and hands-free devices), whereas Bluetooth devices advertise all the services they provide; thus making the service more accessible, without the need to worry about network addresses, permissions, etc.
The Worldwide Interoperability for Microwave Access (WiMAX) is defined by the WiMAX Forum and is embodied in the IEEE 802.16 standard, officially known as Wireless Metropolitan Area Network (WMAN). Many companies are currently considering using WiMAX for “last mile” connectivity at high data rates. In areas that do not have pre-existing physical cable or telephone networks, WiMAX is a viable alternative for broadband access.
WiMAX is a long range system that uses licensed spectrum to deliver a point-to-point connection to the Internet from an ISP to an end user. Different 802.16 standards provide different types of access, from mobile (i.e. access via a cell phone) to fixed which is an alternative to wired access, where the end user's wireless termination point is fixed in location.
WiMAX is a term coined to describe standard, interoperable implementations of IEEE 802.16 wireless networks. The 802.16 MAC uses a scheduling algorithm for which the subscriber station need compete once (for initial entry into the network). After that it is allocated an access slot by the base station. The time slot can enlarge and contract, but remains assigned to the subscriber station which means that other subscribers cannot use it. The 802.16 scheduling algorithm is stable under overload and over-subscription. It is also more bandwidth efficient. In addition, the scheduling algorithm allows the base station to control QoS parameters by balancing the time-slot assignments among the application needs of the subscriber stations.
Regarding the PHY layer, the IEEE 802.16e standard uses scalable orthogonal frequency-division multiplexing (OFDM) and also provides for Multiple Antenna Support through multiple-input, multiple-output. This brings potential benefits in terms of coverage, self installation, power consumption, frequency re-use and bandwidth efficiency. The 802.16e standard also adds a capability for full mobility support.
Regarding spectrum allocation, the 802.16 specification applies across a wide swath of the RF spectrum. There is no uniform global licensed spectrum for WiMAX. In the United States, the biggest segment available is at approximately 2.5 GHz, and is already assigned to carriers (Sprint Nextel and Clearwire). Elsewhere in the world, the most likely bands used will be around 3.5 GHz, 2.3/2.5 GHz, or 5 GHz, with 2.3/2.5 GHz probably being most important in Asia. In addition, several companies have announced plans to utilize the WiMAX standard in the 1.7/2.1 GHz spectrum band recently auctioned by the FCC, for deployment of Advanced Wireless Services (AWS).
The actual radio bandwidth of spectrum allocations is also likely to vary. Typical allocations are likely to provide channels of 5 MHz or 7 MHz. In principle, the larger the bandwidth allocation of the spectrum, the higher the bandwidth that WiMAX can support for user traffic.
The deployment of WiMAX in the United States will be in the 2.5 GHz band. Bluetooth, however, uses the 2.4 GHz band for communications. A problem arises, however, in that the small frequency separation between these two bands does not allow for any meaningful filtering. Simple RF filtering and device blocking performance is not sufficient to provide the required conditions to allow simultaneous operation of these two technologies.
A network diagram illustrating an example prior art network incorporating Bluetooth and WiMAX radios is shown in FIG. 1. The example wireless scenario, generally referenced 10, comprises two mobile devices, namely mobile device A 12 and mobile device B 16, a WiMAX base station 14 and Bluetooth headset 26. Mobile device A comprises a Bluetooth radio 18 as well as a WiMAX radio 20. Similarly, mobile device B comprises a Bluetooth radio 22 as well as a WiMAX radio 24. It is possible that in operation the Bluetooth and WiMAX devices communicate at the same time. Thus, the Bluetooth radio 18 in mobile device A may communicate either with the Bluetooth radio 22 in mobile device B or the Bluetooth headset 26. At the same time, the WiMAX radios 20, 24 communicate with the WiMAX base station 14.
Antenna isolation between the two radios is not likely to provide a good solution. Assuming separate antennas are used, antenna isolation is limited to approximately 15 dB. If both Bluetooth and WiMAX are included on the same handset or other device, their transmissions in effect create blocking and/or degraded sensitivity for the other transceivers receive chain while the other is transmitting. WiMAX transmission is +24 dBm with peaks of +31 dBm. Considering an antenna isolation of 15 dBm, this yields +9 dBm to +16 dBm on the Bluetooth terminal. Such a high level of input power could damage the Bluetooth transceiver.
It is thus desirable to have a mechanism that is capable of enabling a Bluetooth and WiMAX radio to coexist in the same mobile device. The coexistence mechanism should not cause performance degradations in either the Bluetooth or WiMAX radios and should have a minimal impact on cost and required resources in its implementation.